Migratory Bird Initiative

The Philadelphia Zoo and Audubon Pennsylvania have been working in partnership for nearly a decade to study and protect resident and migratory birds. During that time, we have remained largely focused on the issue of window collisions which claims the lives of 100 million-1 billion birds in North America each year.

Birds don’t perceive glass as a solid object, often colliding with windows after flying towards reflected habitat or attempting to fly through glass that’s transparent. A large percentage dies as a result of the impact, while others sustain injuries that lead to death shortly after. Most resident birds have learned to avoid this issue, while unsuspecting migrants are taken in by habitat reflections or the transparency of glass.

Overall, little is being done to address the problem which may be due to a lack of awareness combined with a lack of easy access to bird-friendly solutions. The Zoo and Audubon PA are working with others to change this.

Center City

Migration routes often follow major river systems, making urban areas like Philadelphia critical stopovers for birds migrating between their North American breeding grounds and South American wintering grounds.
Philadelphia lies within the Atlantic Flyway, and both the Delaware and Schuylkill Rivers are important migratory bird corridors in the Delaware River Watershed.

Typically bird collisions with glass will happen more frequently during spring and fall migration periods and can occur just as easily at suburban homes and office parks as in cities with tall buildings. It has also been noted that higher collision rates are found in areas with large numbers of trees and shrubs where the vegetation probably attracts more migratory birds.

In September 2008, the Zoo, Audubon Pennsylvania and the Academy of Natural Sciences began a multiyear study of the bird collision problem in Philadelphia to:

Determine how many birds and which species of birds were being killed or injured in Philadelphia each year.

Identify where collisions are occurring within the City.

Determine when during the day or night collisions are occurring.

Determine which aspects of building design and building operation were associated with bird collisions.

Thanks to many “early bird” volunteers, who monitored for deceased and injured birds in the early am hours, we now know that approximately 1,000 collisions occurred each year within the 3 ½ square block Center City study area alone.

It is hoped that the study’s results will ultimately encourage building owners in Philadelphia to voluntarily act to reduce collisions at their buildings to the degree that that is possible.

Simple steps like turning off certain building lights at night and/or placing blinds in certain windows may help to reduce collisions at buildings with high rates of mortality. Plastic films with patterns can also be placed on the outside of windows to give birds a visual cue that a solid object is ahead. A particularly effective window film has horizontal lines that come in black, white or gray.

Scientists and conservationists from the Zoo and Audubon PA continue to work with architects, building managers, glass manufacturers and the public to raise awareness of this global issue and implement solutions that will decrease bird collisions with glass.

Temple University

During the spring of 2009, as an expansion of our work in Center City, Philadelphia, the Zoo and Audubon Pennsylvania organized a survey of bird collisions on the main campus of Temple University in conjunction with Temple’s Office of Sustainability, Grounds Department and interested students and faculty. Student volunteers were recruited to monitor 12 buildings that were believed to be among the most collision prone buildings on the main campus. A total of 53 birds representing 15 species were found over the course of three weeks during spring migration.

As a result of these findings, a student-led pilot study targeting a campus “collision hotspot” was conducted in the fall of 2010. Data was collected before and after a film matrix was applied over a large area of glass, demonstrating both the problem and the outcome of a solution.

In the fall of 2011, the Zoo and Audubon PA collaborated with Temple’s Tyler School of Art to engage Graphic & Interactive Design students in a semester long “Bird’s Eye View” design competition. Participating students developed aesthetically appealing patterns that could also be collision deterrents when placed on windows.

Working in tandem with their Office of Sustainability, the 2010 pilot study has expanded into different areas of Temple’s main Campus and continues to educate and engage students in working to protect migratory birds.

We’ve taken a variety of steps to reduce or eliminate bird strikes on Zoo grounds, where habitat reflections and transparency can both be issues. Similar to our Center City and Temple University studies, we have gathered data to identify places with the greatest number of collisions within the Zoo. Surveys were led by our keepers as part of their conservation work with the American Association of Zookeepers (AAZK).

At “Bear Country,” you’ll find a horizontal-striped window film that alerts birds to the presence of glass in plenty of time to change course. Above the film is a patterned border that mimics the frosted glass in our McNeil Avian Center, where migration and bird-friendly action steps are a focal point.

The McNeil Avian Center utilizes a frosted glass pattern on all exterior windows and interior glass doors that our collection birds could have contact with and also features an educational film in “Migration Theatre” that tells the story of Otis, an endearing Baltimore oriole setting out on his first migration after hatching here in Fairmount Park.

Ornilux glass has replaced ordinary glass on the doors of a building with habitat reflection issues. Ornilux is a bird-friendly product that has a patterned UV-reflective coating designed to be visible to birds while remaining transparent to the human eye. This is so because birds can see a broader UV spectrum than people.